Infectious bronchitis (IB) is a major disease in the poultry industry and can be associated with respiratory diseases, nephritis, fertility problems and reduced egg production or quality. The disease is caused by infectious bronchitis virus (IBV), a member of the Coronaviridae family (Cavanagh & Gelb, 2008). IBV is primarily a respiratory pathogen. The IBV genome is a single-stranded linear RNA molecule. The IBV virion contains four structural proteins, including the S glycoprotein, which is proteolytically processed into two peptides known as S1 and S2. Nucleotide sequencing of the S1 gene region is considered as the most useful technique for differentiation between distinct IBV strains and for IBV strain classification (Worthington et al., 2008).
Epidemiological studies show that different strains of IBV exist depending on the clinical manifestations and geographic regions. Various IBV strains have been isolated in the art, including, e.g., the Mass serotype, the 793B serotype, the D274 variants, the QX type or the BR type, and the GA08 or the GA13 IBV strains. Vaccination against IBV is only partially successful because of the emergence of antigenic variants and the diversity of IBV strains. Consequently, efficient vaccination requires either IBV cocktails, or the previous identification of the IBV strain prevalent in the field, and/or an IBV strain having a strong immunogenic power. Accordingly, there is a need in the art for novel IBV strains allowing the development of improved vaccines and diagnostic methods.